An air filter designed to remove particulate matter from an airstream generally is a device comprising fibrous materials. These fibrous materials can remove solid particulates such as dust, pollen, mold, and bacteria from an airstream. Air filters are used in applications where air quality is important, notably in heating, ventilation, and air conditioning (HVAC) systems of buildings. HVAC systems generally operate to provide optimal interior air quality to occupants within interior spaces of buildings. HVAC systems achieve optimal interior air quality by conditioning air, removing particle contaminants by way of ventilation and filtration of air, and providing a proper interior pressurization.
While there are many different HVAC system designs and operational approaches, and each building design is unique, HVAC systems generally share a few basic design elements. For example, outside air (“supply air”) generally is drawn into a HVAC system through an air intake. Once in the HVAC system, the supply air is filtered to remove particle contaminants, then heated or cooled, and then circulated throughout the interior space of the building by way of an air distribution system. Many air distribution systems comprise a return air system configured to draw air from the interior building space and return the air (“return air”) to the HVAC system. The return air may then be mixed with supply air and then filtered, conditioned, and circulated throughout the interior space of the building. In some instances, a portion of the air circulating within the building may be exhausted to the exterior so as to maintain a desired barometric pressure within the building.
As will be appreciated, the effectiveness of the HVAC system to provide an optimal interior air quality depends largely on an ability of an air filter within the HVAC system to remove particle contaminants from the air within the building. A HVAC system air filter typically comprises fibrous materials configured to remove solid particulates, such as dust, pollen, mold, and bacteria from the air passing through the HVAC system. Filters may be made from paper, foam, cotton, spun fiberglass, or other known filter materials. The filter material may also be pleated so as to increase the surface area and, accordingly, increase the efficiency of the filter. As will be appreciated, an increase in the number of pleats for a given area will proportionally increase the surface area and therefore the efficiency of the filter.
A drawback to conventional HVAC system air filters is that, as the number or density of pleats increases the ability to maintain a uniform distribution of the pleats within the filter material generally decreases. Even light forces applied to a densely pleated filter, either from handling during installation of the filter unit or from air flow pressure during use, may dent or bend the pleats out of position. Where pleats are compressed together the surface area of the filter will be decreased, along with the efficiency of the filter. This decrease in efficiency may reduce the effective life of a filter is prompting the filter to be discarded prematurely in an effort to increase HVAC system airflow and thus decrease operation costs. Considering the innumerable number of buildings with HVAC systems throughout the world, the volume of discarded air filters that could be eliminated from landfills is staggering.
What is needed, therefore, is a compound air filter that is configured to maintain a uniform distribution of pleats, during installation and use, in order to maximize surface area and overall efficiency of the filter.